1. Field of the Invention
This invention relates generally to endless conveyor belt cleaning systems, and more particularly to a nozzleless conveyor belt sprocket support shaft that discharges a cleaning fluid through a plurality of narrow slits to clean the belt, sprockets, and bearings while the conveyor is operating.
2. Background Art
Conveyors comprising sprocket-driven endless belts are typically used for the transport of many articles including produce and food products. The items being transported may leak or ooze liquids of varying viscosity, or shed dust, dirt, particles or debris that can accumulate on the belt and foul the conveyor. In food processing plants, where cuts of meat, poultry, fish and other consumable food products are transported on conveyors, sanitation is a primary concern, because these types of food products ooze blood, deposit viscous or congealed fat, cartilage, muscle, and other animal carcass liquids and debris onto the belt and other components of the conveyor system. Such organic matter, if allowed to accumulate on the belt and/or other components, presents a health hazard because it quickly decays, and can cause growth of bacteria, biofilms, and cross-contamination. Thus, the conveyors must be maintained in a clean and hygienic condition to meet sanitary standards. Some regulations require that the food conveyor be washed-down several times a day, and be taken apart and completely cleaned every twenty-four hours. The cleaning requirements cause a necessary, but time-consuming, downtime of the equipment and delay in production, and additional time and effort must be expended to re-assemble the conveyor.
“Modular” or “table top” type conveyors are widely used in food handling and processing, wherein the conveyor belts or chains are made of a series of small modules or links formed of temperature resistant easily cleanable plastic material that are interconnected in laterally adjacent relation in a hinge-like manner by connection pins or rods installed through overlapping apertures in the modules or links to form an endless loop. One end of the endless belt passes over one or more drive sprockets, and its opposed end passes over one or more idler sprockets.
One of the major problems with these types of conveyor systems is that, organic matter and the various liquids and debris tend to work their way into and through crevasses, joints, hinges, interfaces and openings in the belt and a substantial amount of unwanted organic matter thereby accumulates on the inside surface of the belt and on the drive components such as the drive sprockets, idler sprockets and support rollers. Generally, the inside surface of the belt and the drive components are not easily accessible for cleaning, requiring that the conveyor be regularly shut down and disassembled to effect a thorough cleaning.
Another problem with these types of conveyor systems is that the structural components and the drive and idler sprocket assemblies are constructed and/or assembled in a manner that produces ledges, pockets, exposed screw threads, exposed nuts or fasteners, surfaces that overlap and form laminations, all of which also tend to accumulate liquids and debris from the food being transported and present a health hazard due to growth of bacteria, biofilms, and cross-contamination.
Several conventional approaches to cleaning conveyor systems include dismantling the system and manually cleaning the components by hand, or providing cleaning devices as part of the conveyor system, such as a roller to rinse the belts, spraying systems utilizing nozzles to spray cleaning fluids onto the belts, or scrubbers and brushes that engage the belts.
There are several patents directed toward various cleaning apparatus that utilize nozzles installed on sprockets, or nozzles installed on the shaft that support the sprockets. As used herein, the term “nozzle” has its usual definition; e.g., “a projecting part with an opening, as at the end of a hose, for regulating and directing a flow of fluid” (The American Heritage® Dictionary of the English Language, Fourth Edition), or “a short tube with a taper or constriction used (as on a hose) to speed up or direct a flow of fluid” (Merriam-Webster Online Dictionary). The term “slit” has its usual definition; e.g., “a long, straight, narrow cut or opening” (The American Heritage® Dictionary of the English Language, Fourth Edition), or “a long narrow cut or opening” (Merriam-Webster Online Dictionary).
Montgomery, U.S. Pat. No. 6,367,613 and Published Application 2002/0117381 discloses a single elongate longitudinal sprocket adapted to spray a fluid for cleaning an endless conveyor belt. The elongate sprocket has a width substantially the same as the width of the conveyor belt, an outer circumferential surface with radially spaced longitudinal teeth for supporting an inwardly facing surface of the belt, a fluid conduit extending lengthwise within the body from one end thereof, and a plurality outlet passages formed in the sprocket extending radially from the fluid conduit terminating in apertures disposed in the valley between the teeth positioned along the length of the sprocket in a helical path, and nozzles are preferably fitted in the apertures between the teeth.
One of the disadvantages of the single elongated sprocket cleaning system of U.S. Pat. No. 6,367,613 and Published Application 2002/0117381 is that the plurality of nozzles project from the valley surface of the sprocket between radially spaced longitudinal teeth, thus, the nozzles and sprocket assembly provides exposed projecting surface areas that could accumulate liquids and debris and promote growth of bacteria, biofilms, and cross-contamination. The placement of the nozzles also limits the coverage area for fluids being emitted from the nozzles onto the conveyor belt.
Griffiths, et al, U.S. Pat. No. 6,740,172 discloses a modular belt-cleaning apparatus having sprockets rotatably mounted on a non-rotating hollow shaft. Each sprocket includes a first pair of diametrically opposed generally pie-shaped sectors and a second pair of diametrically opposed generally pie-shaped sectors that are laterally staggered in relation to the first pair of sectors to provide a space therebetween. The pie-shaped sprocket sectors are mounted on hubs fixed to the shaft by set screws or snap rings. Each sprocket is flanked by a pair of nozzles mounted on the stationary hollow shaft, each of which produces a fan-shaped spray that overlap one another across the lateral extent of the conveyor belt and are angled relative to one another so as not interfere with one another, and the nozzles are positioned to clean the hinges of the belt when the hinges are open.
One of the disadvantages of the pie-shaped sector sprocket assembly of U.S. Pat. No. 6,740,172 is that the nozzles and set screws or snap rings provide exposed screw threads and projecting surface areas, and the laterally mounted pie-shaped sectors and hubs provide overlapping surfaces, which could accumulate liquids and debris and promote growth of bacteria, biofilms, and cross-contamination. The nozzle and sprocket arrangement also requires time and labor to remove and reinstall a plurality of nozzles each time a sprocket is replaced, or when the sprocket assembly is dismantled for cleaning. The nozzles are also fixed to the non-rotating shaft and do not rotate along with the conveyor belt, which limits the coverage area for fluids being emitted from the nozzles onto the conveyor belt.
Barrett, U.S. Pat. No. 6,978,880 discloses a conveyor belt cleaning bar having a first end, a second end, a mid portion having a square-shaped transverse cross section, a plurality of nozzles fitted into apertures in the square-shaped mid portion to extend outwardly from the outer surface of the mid portion, and sprockets having a square-shaped bore installed on the outer surface of the square-shaped mid portion, with at least one of the sprockets disposed between at least two nozzles. The nozzles define a spray pattern that surrounds the bar and converges upon the entire width of a conveyor belt.
One of the disadvantages of the conveyor belt cleaning sprocket assembly of U.S. Pat. No. 6,978,880 is that the outwardly extending nozzles provide exposed screw threads and projecting surface areas, and the square bar and bore of the mounting arrangement of the sprockets provides overlapping flat surfaces, which could accumulate liquids and debris and promote growth of bacteria, biofilms, and cross-contamination. The nozzle and sprocket arrangement also requires time and labor to remove and reinstall a plurality of nozzles each time a sprocket is replaced, or when the sprocket assembly is dismantled for cleaning.
The present invention overcomes the aforementioned problems and is distinguished over the prior art in general, and these patents in particular by a nozzleless belt-cleaning sprocket support shaft for cleaning endless conveyor belts and the sprockets supported thereon. The shaft has a first end, a second end, a central portion of generally square transverse cross section with a plurality of elongate narrow slits in each of the side walls in longitudinally spaced apart relation along its length, and a plurality of sprockets mounted thereon. Cleaning fluid is simultaneously discharged through the slits in a fan spray pattern onto the inside surface of the conveyor, through crevasses, joints, hinges, interfaces and openings in the belt to effect cleaning of the belt, and between the exterior surfaces of the shaft and interior surfaces of the bores of the sprockets and the bearings that support the shaft to effect cleaning of the overlapping surfaces, during rotation of the belt. The ends may also be configured for use with conventional bearings.